Such cameras that have a wide-angle lens covering a wide field of vision are used for many purposes, like as a security camera, an observatory camera for observing crops or disasters, a camera for on-the-spot inspection, a camera for recording sport events, or a TV camera. A super-wide angle camera using a fisheye lens is also well known. As covering a wide field of vision, the camera with the wide-angle lens or the fisheye lens can record the whole information of the subjects existing in a wide range of the field.
On shooting or broadcasting some sport event or the like, also a camera using a telephoto lens or a zoom lens has been used for close-upping important incidents of the events with higher sharpness. Because the field of vision of the telephoto lens and that of the zoom lens at a long focal length is narrow, the camera continually follows the subject, e.g. an individual player, in order to capture a scene at the important moment.
With the camera using the wide-angle lens, the captured images do not provide detailed information on individual subjects, and the sharpness of the images is inferior. On the contrary, with the camera using the telephoto lens or the zoom lens, it is possible to capture a clear image of the particular subject, such as a player, which is followed by the camera. However, it is impossible to obtain pictorial information of other scenes outside the field of the telephoto lens or zoom lens.
To solve the above problems, it has conventionally been done using a plurality of cameras for taking many subjects simultaneously in a wide range of field, wherein each camera uses a lens whose field is not so wide as the fisheye lens or the wide-angle lens but not so narrow as the telephoto lens or the zoom lens. The plurality of cameras are located dispersedly and activated continuously. For example, Japanese Laid-open Patent Application Hei 09-139878 discloses such a solution.
However, for use as security cameras or observatory cameras, it is necessary to install a certain number of cameras in order to reduce blind spots. For shooting or relay broadcasting a sport event by a plurality of cameras, it is necessary to dispose at least an operator for each camera. In addition, if the camera operator fails to follow every movement of a subject, the camera does not catch some information on the subject.
To solve this problem, the present applicant invented an imaging system using a multi-focus camera that is provided with a lot of imaging units of different focal lengths. But it has been difficult to take an in-focus image of every subject at every place in the shooting space. It has also been difficult to take images in the same size from those subjects which are equal in size, if these subjects exit at different places in the shooting space.